The couple, which met on the set of 2005 movie Pride & Prejudice, decided to end its five-year relationship shortly before Christmas, according to the actress' father Will.

But Knightley has refused to wallow in self-pity at home, and hit the streets of London for a night of sing-along fun with friends, including her The Edge of Love co-star Miller.

The group showed off their vocal skills on tracks such as Queen's "Don't Stop Me Now" and Bon Jovi's "Livin' On A Prayer" while drinking Cosmopolitan cocktails at the Lucky Voice karaoke bar, according to Britain's The Sun.

A source tells the newspaper, "It was a pretty raucous affair. The girls went really crazy for Cosmopolitans. They weren't holding back at all.

"There were about 12 people in the group, but no diva-like antics. They all got stuck in (involved)."